The Collaborative International Dictionary of English v.0.48:

Dissoluble \Dis"so*lu*ble\, a. [L. dissolubilis: cf. F.
   dissoluble. See Dissolve, and cf. Dissolvable.]
   1. Capable of being dissolved; having its parts separable by
      heat or moisture; convertible into a fluid. --Woodward.
      [1913 Webster]

   2. Capable of being disunited.
      [1913 Webster]

WordNet (r) 3.0 (2006):

dissoluble
    adj 1: capable of dissolving [syn: dissolvable, dissoluble]